To import graphics from a file, select File > Import… from the main menu and choose a file. Alternatively, you can drag and drop an image from Finder to your document. These methods can be used with SVG files as well as with other formats such as TIFF, PNG, JPEG, PDF and EPS.
If you want to fill a shape with an image, use the Color panel. Note that the Color panel does not support the SVG format.